1. WUR MAC issues follow-up
March 2017
WUR MAC issues follow-up
Date:
Authors:
Name
Affiliation
Address
Phone
Jeongki Kim
LG Electronics
19, Yangjae-daero 11gil, Seocho-gu, Seoul , Korea
Kiseon Ryu
Suhwook Kim
Jinsoo Choi
Jeongki Kim et al, LG Electronics

2. March 2017
Abstract
The following several WUR MAC issues were discussed at the previous meetings [1] and there were some agreements among them
Broadcast Wake-up
Group wake-up
Multicast Wake-up
WUP (Wake Up Packet) contents design
This contribution discusses details of them and proposes the related SFD texts
Jeongki Kim et al, LG Electronics

3. Broadcast Wake-Up (1/4) March 2017
For WUR mode STAs to receive Beacon or Group addressed BU through PCR, AP can send a broadcast wake-up packet to wake up all WUR mode STAs which are associated with the AP
Broadcast WUP should be sent early with enough time for those WUR mode STAs to receive Beacon/GA BU correctly after their wake up delay
Because Broadcast WUP TX can be delayed if channel is busy and,
Each STA’s wake-up delay could be different according to each STA’s capability or its environment
Broadcast Wakeup
Beacon/
Group addressed BU AP
Wakeup delay
Waiting time
STA1
WLAN on
STA2
WLAN on
STA3
WLAN on
STA4
WLAN on
Jeongki Kim et al, LG Electronics

4. March 2017
Broadcast Wake-Up (2/4)
AP informs the STAs of the Wake-up Completion Time (WCT)
WCT means the time at which WUR mode STA should finish its wake up procedure to receive the DTIM or Group addressed BU correctly
How to set the WCT by AP is out of this standard. It’s AP’s implementation
Because the WCT value is decided when the broadcast WUP is transmitted, WCT should be included in broadcast wake-up packet
Each WUR mode STA decides its WLAN-On start time based on the received WCT value and its wake up delay
AP sends WLAN frame (e.g., Beacon, Group addressed BU) through PCR after the WCT
Jeongki Kim et al, LG Electronics

5. Broadcast Wake-Up (3/4) March 2017
Example 1 (Beacon reception): AP sets WCT to TBTT
Upon receiving Broadcast WUP, WUR mode STA finishes its wake up procedure until WCT and waits to receive Beacon frame
In this case STA can update the system information based on the information in the received Beacon
Broadcast Wakeup
(WCT)
WCT
Beacon AP
Wake up start time of STA 1, 2
Wakeup delay
STA1
WLAN on
STA2
WLAN on
STA3
WLAN on
Wake up start time of STA 3, 4
STA4
WLAN on
Jeongki Kim et al, LG Electronics

6. Broadcast Wake-Up (4/4) March 2017
Example 2 (Group addressed BU reception): AP sets WCT to the transmission time of group addressed BU
Upon receiving Broadcast WUP, WUR mode STA finishes its wake up procedure until WCT and waits to receive Group addressed BU frame
Broadcast Wakeup
(WCT)
WCT
Group addressed BU AP
Wake up start time of STA 1, 2
Wakeup delay
STA1
WLAN on
STA2
WLAN on
STA3
WLAN on
Wake up start time of STA 3, 4
STA4
WLAN on
Jeongki Kim et al, LG Electronics

7. TF reception after WCT March 2017
The AP can send a Trigger Frame in 11ax to solicit response frames from one or more STAs after sending a wake-up packet to the STA(s). [Motion 3, March 2017]
In this case, AP can also include WCT (wake-up completion time) in WUP (s) before sending the Trigger frame so that STA can decide its WLAN-On start time
WUP (STA 1, 2, 3), WCT
WCT TF
MU PPDU (STA 1, 2, 3) AP
Wakeup delay
Wake up start time
PS-Polls from STA 1~3
STA1
WLAN on
STA2
WLAN on
STA3
WLAN on
STA4
Jeongki Kim et al, LG Electronics

8. Group wake-up March 2017 Group wake up
Group wake up (e.g., using Group ID) can be used for waking up all STAs belonging to a group but it hardly happens
May not be efficient if it is used for waking up a part of STAs in a group  increasing false alarm
Need complicate group management like MU-MIMO
WUP
(GID =1)
MU PPDU (STA 1, 2, 3) AP
Wakeup delay
PS-Polls from STA 1~5
STA1
WLAN on
STA2
STA3
STA4
Unnecessary power consumption
STA5
Unnecessary power consumption
STA1, 2, 3, 4, 5 belong to Group 1 (GID=1)
Jeongki Kim et al, LG Electronics

9. Multi-User Wake-Up (1/2)
March 2017
Multi-User Wake-Up (1/2)
1) WUR ID can be allocated before entering WUR mode
Multi-User (MU) Wake Up
WUR needs to support MU wake-up mode for waking up a part of STAs in a group
Example 1) WUP may contain multiple receiver IDs  the WU packet size is increased according to the number of STAs
Example 2) WUP may contain the STA’s position bitmap like TIM
TIM size should be optimized (e.g., like 11ah hierarchical TIM or using WUR ID1) instead of AID)
A STA should also send a response frame to the AP after receiving MU wake-up packet which is sent for unicast WLAN frame
WUP (STA 1, 2, 3) D1 D2 D3 AP
Wakeup delay
PS-Poll
STA1
WLAN on
PS-Poll
STA2
WLAN on
PS-Poll
STA3
WLAN on
STA4
Jeongki Kim et al, LG Electronics

10. Multi-User Wake-Up (2/2)
March 2017
Multi-User Wake-Up (2/2)
Example 1
Total length (M)
WUR frame type = a: M= 2 (bytes)
WUR frame type = a+1: M= 3 (bytes)
WUR frame type = a+2: M= 4 (bytes)
Total length = M bytes
Starting ID = X
Bitmap …
X+1
X+2
X+n
Jeongki Kim et al, LG Electronics

11. WUP contents format (1/2)
March 2017
WUP contents format (1/2)
Considerations on Wake-Up Packet (WUP) contents design
WUP TX frequency as small as possible to minimize the contention with other WLANs/WUPs  Broadcast/Group/MU wake up
WUP content size should be minimized (e.g., if OOK is used, 1 symbol (4us) is used for delivering 1 bit)  WUP optimization
Avoid unnecessary false alarm of wake-up  MU wake-up instead of group wake up
Including WUR operation mode (WOM) information which indicates the STA’s operation after receiving the WUP
Whether the STA should wake up after receiving the WUP or not
WUP may be sent for just keep alive check or synchronization(WUR beacon reception). In this case STA does not need to wake up
Whether the STA should send a response frame (e.g., PS-Poll) based on EDCA though primary connectivity radio after turning on the main radio or not
E.g., Sending a response for unicast WUP, not sending a response for a broadcast/multicast WUP for group-addressed data TX, may not be sending a response for a WUP for MU polling
This information is necessary for supporting the following motion text
A STA should send a response frame to the AP using primary connectivity radio after receiving a unicast wake-up packet. [Motion 1, March 2017, see [1] [6]]
Jeongki Kim et al, LG Electronics

12. WUP contents format (2/2)
March 2017
WUP contents format (2/2)
Various WU packet types according to different length
Frame Type & Receiver ID
0: WUR Beacon
1: Broadcast wake-up, Receiver ID does not need to be included
2: Individual wake-up, Individual ID is included
3: MU wake-up, Multiple ID information (e.g., TIM or multiple IDs set) are included instead of individual ID
WOM(WUR Operation Mode)
0- No wake-up, 1- Wake-up and EDCA access, 2- Wake-up and No EDCA access
WOM can be merged with Frame Type field
Transmitter ID: Partial BSSID (or BSS Color)
WCT (Wake-up completion time): the time at which WUR mode STA should finish its wake up procedure (slides 4, 5).
AP sends a frame to STA (s) through the primary connectivity radio after the WCT
STA can determine its WLAN On Start time based on the WCT
Frame Type
(WOM)1)
Transmitter ID
Receiver ID (optional)
WCT
FCS
FT=0
(WOM)
Transmitter ID
Timestamp[2]
FCS
FT=1
(WOM)
Transmitter ID
WCT
FCS
FT=2
(WOM)
Transmitter ID
Individual ID
WCT
FCS
FT=3
(WOM)
Transmitter ID
Multiple ID Info
WCT
FCS
Jeongki Kim et al, LG Electronics

13. March 2017
Conclusion
For power saving of WUR STAs, AP includes the WCT in a wake-up packet (WUP)
WUR STA decides when it turns on the primary connectivity radio after the WUP based on the WCT and its wake-up delay
AP sends WLAN frame to a STA through the PCR after the WCT
A multi-user wake-up packet includes the information of multiple STAs which need to wake up (e.g., multiple IDs or Bitmap type)
A STA should also send a response frame to the AP after receiving MU wake-up packet which is sent for unicast WLAN frame as well as after receiving unicast wake-up packet
Wake-up packet has different types according to its packet length and includes the frame type field for it
WU packet design contains the information for the STA’s operation after receiving WUP (e.g., WUR operation mode (WOM))
0: No-wake up, 1: wake-up and EDCA access, 2: wake-up and waiting w/o EDCA
Jeongki Kim et al, LG Electronics

14. References [1]11-17/0054, WUR MAC issues
March 2017
References
[1]11-17/0054, WUR MAC issues
[2] ba-wur-beacon
Jeongki Kim et al, LG Electronics

15. Straw Poll 1 Do you support the following?
March 2017
Straw Poll 1
Do you support the following?
A broadcast wake-up frame (B-WUF) includes the information to indicate the deadline on which WUR mode STAs should complete its wake up procedure after receiving the broadcast WUF
Jeongki Kim et al, LG Electronics

16. Straw Poll 2 Do you support the following?
March 2017
Straw Poll 2
Do you support the following?
A multi-user wake-up frame (MU-WUF) contain the information to identify the multiple STAs
The detailed identification (e.g., multiple individual identifiers, group bitmap or User bitmap, etc.) is TBD.
Jeongki Kim et al, LG Electronics

17. Straw Poll 3 Do you support the following?
March 2017
Straw Poll 3
Do you support the following?
User bitmap is included in an MU wake-up frame as the information to identify the multiple WUR mode STAs
The details of bitmap is TBD
The size of the information to identify the multiple STAs will not be larger than 4 bytes
Jeongki Kim et al, LG Electronics

18. Straw Poll 4 Do you support the following?
March 2017
Straw Poll 4
Do you support the following?
A wake-up frame (WUF) contains the 4-bit WUF Type field to indicate the type of the WUF
WUF Type = 0: WUR Beacon
WUF Type = 1: Individual wake-up
WUF Type = 2: Broadcast wake-up
WUF Type = 3: Multi-user wake-up
Jeongki Kim et al, LG Electronics

19. Straw Poll 5 Do you support the following?
March 2017
Straw Poll 5
Do you support the following?
Broadcast wake-up frame (B-WUF) does not carry the receiver ID
Jeongki Kim et al, LG Electronics

20. Straw Poll 6 Do you support the following?
March 2017
Straw Poll 6
Do you support the following?
A wake-up frame (WUF) contains the following information to indicate the STA’s operation after the WUR mode STA receives the wake-up packet
Whether the WUR mode STA wakes up after receiving the WUP or not
Whether the STA sends a response frame (e.g., a PS-Poll) after waking up from WUR mode or not
The detailed indication method (e.g., explicit or implicit like Type field) is TBD
Jeongki Kim et al, LG Electronics